The present invention relates to a method and apparatus for weighing packages of the type comprising a hollow winding tube having yarn or similar material wound thereupon.
A weighing apparatus of the described type is disclosed in DE OS 29 45 861 and corresponding U.S. Patent RE 31,839. The weighing apparatus disclosed therein is used for the quality control of full yarn packages in a continuous spinning process, and they continuously register the weights of the fully wound yarn packages and input the same via a suitable evaluation circuit to a control unit, which readjusts the necessary control parameters, if need arises, so as to ensure a uniformly high quality.
In accordance with the known weighing apparatus, the measured weighing data are transmitted via so-called tow lines to a process computer, the tow lines being needed so as to obtain the necessary freedom of movement for the package transport units. A requirement for this system is that the package transport units are adapted for traveling only in a reciprocal movement, and for this reason, it is necessary always to have all package transport units move in a uniform direction, so as to preclude a mutual interference.
It is possible, however, to provide without any difficulties a multitrack package transport system, it being necessary that each of the individual tracks have a forward and a return track, so as to be able to operate several package transport units at the same time. This alternative would involve a significant cost, and in addition, the requirements to be met by modern spinning systems with independent time cycles for each spinning machine, control station and, possibly, temporary storage, will not as a practical matter allow such solutions.
Furthermore, while it is conceivable to have the package transport units travel independently of one another via a radio control system, the problem arises that it is necessary to select a separate frequency for each package transport unit, so as to avoid having the radio signals of the individual package transport units interfere with one another.
It is accordingly an object of the present invention to provide an improved weighing apparatus of the described type which is able to achieve a high weighing throughput in an economical manner, with small space requirements, and irrespective of the preset time cycles of individual production areas of the spinning system.